import java.util.Properties;
import java.util.Set;

public class PropertiesDemo {
    public static void main(String[] args) {
        Properties prop = new Properties();
        prop.put("1001","Jack");
        prop.put("1002","Nancy");
        prop.put("1003","May");
        Set<Object> keySet = prop.keySet();
        for(Object value : keySet){
            Object o = prop.get(value);
            System.out.println(value + " " + o);
        }
    }
}
